Has anyone use q-bert with a vga converter?

Dr. Willy

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I acquired a q-bert cocktail that was mussing it's 13" monitor. I have. 17" wells d9100 that in found will fit in the cabinet however the 9100 is vga input only.

I know q-bert is positive sync so I changed the 7407 at j14 to make the sync negitve then ran both of them together and wired them up to a gonbes 9200 vga converter. Hooked up th vga monitor and I have a picture but it won't lock reliable. It will jump around about every 15 sec in random directions.

Has anyone successfully used a vga converter with qbert weather it be in a cab or bench testing setup?
 
Sounds like a candidate for a jrok

I'm not quite sure what you mean. I didn't know anything about these jrok boards, but just googled them. And as far as I can see, they don't output VGA... and they all seem to expect comp sync at the input...
 
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If the converter takes negative composite sync, you can not just run the 2 signals together without a gate. I had a I similar problem some years ago. Depending on if you combine signals before or after inversion, you should use either an AND or an OR gate...

Details on what I did is in these 2 FB-posts:

https://m.facebook.com/story.php?story_fbid=139106149593064&id=137999229703756

https://m.facebook.com/story.php?story_fbid=139276496242696&id=137999229703756

So seeing how I already changed the 7407 to a 7406 and the board is putting out negitive h and v sync sounds like I need an AND gate. I'm still learning my way through IC's can you pint me in the direction to one that will work?
 
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